Non-Fluorinated Dual-Solvent Electrolyte for High-Performance Zinc-Based Energy Storage

Here, we report novel electrolytes based on fluorine-free (F-free) salt zinc methanesulfonate (ZMS) in N,N-dimethylpropyleneurea (DMPU) and triethyl phosphate (TEP). While the single-solvent DMPU-based electrolyte exhibited suboptimal performance at 0.5 mA cm–2, the addition of TEP as a dual solvent significantly enhanced the electrochemical performance for over 1000 h at 1 mA cm–2 and up to 2.5 mAh cm–2. TEP modulated the solvation structure of the electrolyte, which facilitated Zn2+ desolvation and promoted uniform zinc plating/stripping, while its partial reduction during initial cycling formed a robust solid electrolyte interphase (SEI) composed of zinc phosphate and organic phosphate species, effectively suppressing the dendrite growth and minimizing side reactions. The dual-solvent electrolyte demonstrated an excellent cycling stability and a high Coulombic efficiency, while the polyaniline (PANI)-based full cell achieved 88% capacity retention at 0.1 A g–1, and ∼80% retention at 1 A g–1 over 500 cycles. Besides, the full cell based on activated carbon (AC) also maintained 76% retention at 0.1 A g–1. This study manifests the potential of the F-free dual-solvent electrolyte for applications in both zinc-ion supercapacitors (ZICs) and zinc-ion batteries (ZIBs).